TiDB Connector for Spark User Guide

The TiDB Connector for Spark is a thin layer built for running Apache Spark on top of TiDB/TiKV to answer the complex OLAP queries. It takes advantages of both the Spark platform and the distributed TiKV cluster and seamlessly glues to TiDB, the distributed OLTP database, to provide a Hybrid Transactional/Analytical Processing (HTAP) solution to serve as a one-stop solution for both online transactions and analysis.

The TiDB Connector for Spark depends on the TiKV cluster and the PD cluster. You also need to set up a Spark cluster. This document provides a brief introduction to how to setup and use the TiDB Connector for Spark. It requires some basic knowledge of Apache Spark. For more information, see Spark website.

Overview

The TiDB Connector for Spark is an OLAP solution that runs Spark SQL directly on TiKV, the distributed storage engine.

TiDB Connector for Spark integrates with Spark Catalyst Engine deeply. It provides precise control of the computing, which allows Spark read data from TiKV efficiently. It also supports index seek, which improves the performance of the point query execution significantly.

It utilizes several strategies to push down the computing to reduce the size of dataset handling by Spark SQL, which accelerates the query execution. It also uses the TiDB built-in statistical information for the query plan optimization.

From the data integration point of view, TiDB Connector for Spark and TiDB serve as a solution runs both transaction and analysis directly on the same platform without building and maintaining any ETLs. It simplifies the system architecture and reduces the cost of maintenance.

also, you can deploy and utilize tools from the Spark ecosystem for further data processing and manipulation on TiDB. For example, using the TiDB Connector for Spark for data analysis and ETL; retrieving data from TiKV as a machine learning data source; generating reports from the scheduling system and so on.

Environment setup

The current version of the TiDB Connector for Spark supports Spark 2.1. For Spark 2.0 and Spark 2.2, it has not been fully tested yet. It does not support any versions earlier than 2.0.

Deploy the TiDB Connector for Spark

Deploy the TiDB Connector for Spark on the existing Spark cluster

Running TiDB Connector for Spark on an existing Spark cluster does not require a reboot of the cluster. You can use Spark’s --jars parameter to introduce the TiDB Connector for Spark as a dependency:

spark-shell --jars $PATH/tispark-0.1.0.jar

If you want to deploy TiDB Connector for Spark as a default component, simply place the TiDB Connector for Spark jar package into the jars path for each node of the Spark cluster and restart the Spark cluster:

${SPARK_INSTALL_PATH}/jars

In this way, you can use either Spark-Submit or Spark-Shell to use the TiDB Connector for Spark directly.

Deploy TiDB Connector for Spark without the Spark cluster

If you do not have a Spark cluster, we recommend using the standalone mode. To use the Spark Standalone model, you can simply place a compiled version of Spark on each node of the cluster. If you encounter problems, see its official website. And you are welcome to file an issue on our GitHub.

Download and install

For the Standalone mode without Hadoop support, use Spark 2.1.x and any version of Pre-build with Apache Hadoop 2.x with Hadoop dependencies. If you need to use the Hadoop cluster, please choose the corresponding Hadoop version. You can also choose to build from the source code to match the previous version of the official Hadoop 2.6. Please note that the TiDB Connector for Spark currently only supports Spark 2.1.x version.

Suppose you already have a Spark binaries, and the current PATH is SPARKPATH, please copy the TiDB Connector for Spark jar package to the ${SPARKPATH}/jars directory.

Start a Master node

Execute the following command on the selected Spark Master node:

cd $SPARKPATH
./sbin/start-master.sh

After the above step is completed, a log file will be printed on the screen. Check the log file to confirm whether the Spark-Master is started successfully. You can open the http://spark-master-hostname:8080 to view the cluster information (if you does not change the Spark-Master default port number). When you start Spark-Slave, you can also use this panel to confirm whether the Slave is joined to the cluster.

Start a Slave node

Similarly, you can start a Spark-Slave node with the following command:

./sbin/start-slave.sh spark://spark-master-hostname:7077

After the command returns, you can see if the Slave node is joined to the Spark cluster correctly from the panel as well. Repeat the above command at all Slave nodes. After all Slaves are connected to the master, you have a Standalone mode Spark cluster.

Spark SQL shell and JDBC server

If you want to use JDBC server and interactive SQL shell, please copy start-tithriftserver.sh stop-tithriftserver.sh to your Spark’s sbin folder and tispark-sql to the bin folder.

To start interactive shell:

./bin/tispark-sql

To use Thrift Server, you can start it similar way as default Spark Thrift Server:

./sbin/start-tithriftserver.sh

And stop it like below:

./sbin/stop-tithriftserver.sh

Demo

Assuming that you have successfully started the TiDB Connector for Spark cluster as described above, here’s a quick introduction to how to use Spark SQL for OLAP analysis. Here we use a table named lineitem in the tpch database as an example.

Assuming that your PD node is located at 192.168.1.100, port 2379, add the following command to $SPARK_HOME/conf/spark-defaults.conf:

TiSparkR

TiSparkR is a thin layer built to support the R language with TiSpark. Refer to this document for usage.

TiSpark on PySpark

TiSpark on PySpark is a Python package build to support the Python language with TiSpark. Refer to this document for usage.

FAQ

Q: What are the pros/cons of independent deployment as opposed to a shared resource with an existing Spark / Hadoop cluster?

A: You can use the existing Spark cluster without a separate deployment, but if the existing cluster is busy, TiDB Connector for Spark will not be able to achieve the desired speed.

Q: Can I mix Spark with TiKV?

A: If TiDB and TiKV are overloaded and run critical online tasks, consider deploying the TiDB Connector for Spark separately. You also need to consider using different NICs to ensure that OLTP’s network resources are not compromised and affect online business. If the online business requirements are not high or the loading is not large enough, you can consider mixing the TiDB Connector for Spark with TiKV deployment.